late 15c., "to punish by a fine," from Middle French mulcter "to fine, punish" (15c.), from Latin mulctare, altered (Barnhart calls it "false archaism") from multare "punish, to fine," from multa "penalty, fine," perhaps from Oscan or Samnite [Klein]. Sense of "defraud" is first recorded 1748. Related: Mulcted; mulcting.